Unstable

"Unstable people are with shaken sanity and must work really hard to maintain it. Starting and maximum Sanity values are decreased, which increases the chance for negative psychological effects."

Unstable is Negative Perk that lowers maximum Sanity to 80 (from 100) and starting Sanity to 50(from 70)

Tips

 * it is possible to get Invigorated level 2 with 80 Sanity, but any negative Sanity change will make you louse it.
 * Even the slightest Sanity drop in the beginning of the game may drop you one of the "Crazy" Conditions: Depressed, Hectic, Terrified, Disoriented, Insomniac
 * Stack on Roasted mushrooms and Grapes as they give +1 Sanity and are the easiest way to quickly recover from rapid Sanity loss.